I've not heard that this is showing up in the various trackers (which of course do change over time), but my gut reaction is that despite the different terminology, an eTA is - for all intents and purposes - simply an electronic visa. They have different names but when you get right down to it, a visa for the purpose of visiting Canada is a 'travel authorization.'
Obviously they do not overlap entirely (eg eta eligible = visa waiver eligible = no visa needed at land crossing, TRVs are issued for some purposes for which etas are not eligible [as I understand it], etc). But I could see why a government system would consider one to be a type of the other and share a number/format esp since they use both for similar purposes i.e. 'clear to board' decisions.
So for that reason I would guess this has nothing to do with nationality but some type of internal system.
I've been wondering for a while why Canada doesn't move to more of these types of electronic travel authorizations / electronic visas, lots of countries have moved to them almost entirely (or the old style are exceptions). I don't see why they couldn't do it for the immigrant visas they issue along with the COPRs, for example. [Caveat that I'm sure there are what IRCC considers to be 'good reasons', not my business what they are; but for countries whose passports comply with the most recent ICAO/etc recommendations and standards, I'm a bit stumped as to what those would be and it seems to me the gains of switching to electronic are pretty darn substantial.]
